Method for combustion of metals



M 25,, 1956 A. v. GROSSE EJ64 109 METHOD FOR COMBUSTION OF METALS FiledNov. 50, 1953 4 Sheets-Sheet l INVENTOR ATTORN EY p 1956 A. v. GROSSEMETHOD FOR COMBUSTION 0F METALS Filed Nov. 30. 1953.

4 Sheets-Sheet 2 INVENTOR W ATTORN Smph 25, 1956 A. v. GRQSSE METHOD FORcomsuswzom OF METALS 4 Sheets-Sheet 3 Filed NOV. 30, 1953 INVENTOATTORNEY p 25, 56 A v. GROSSE 2,764,109

METHOD FOR COMBUSTION OF METALS Filed NOV. 30, 1953 4 Sheets-Sheet 4 is60 fl aflame Jr 786/9 1 y 40 K- 20 X L wfizgz k ATTORN United StatesPatent METHOD FOR COMBUSTION 0F METALS Aristid V. Grosse, Haverford, Pa.Application November 30, 1953, Serial No. 395,160 6 Claims. (Cl. 110-1)This application is a continuation-in-part of my copending applicationSerial No. 260,424, filed December 7, 1951, and now abandoned.

This invention relates to the production and application of heat fromthe combustion of aluminum, magnesium, zirconium and related metals.More particularly this invention relates to combustion of a highlyexothermic metal in a manner to concentrate and accumulate the heat.

It is an object of this invention to provide a temperature of a highdegree by the combustion of highly exothermic metals.

It is a further object of this invention to provide a means forcombustion of highly exothermic metals which concentrates andaccumulates the heat produced.

A still further object of this invention is the provision of a furnacefor the combustion of aluminum, magnesium, zirconium and similar metalswhich applies the heat produced to create unusually high temperatures.

Another object of this invention is to provide a torch burning aluminum,magnesium, or zirconium or similar metals which produces extremely hightemperatures.

It is still another object of this invention to provide a process formelting or penetrating a ceramic, concrete or stone object.

It is a further object of this invention to provide a process ofcombustion which will penetrate a ceramic, concrete or stone object.

These and other objects of this invention will become apparent uponconsideration of the following description taken together with theaccompanying drawings in which:

Fig. l is a section of a furnace according to this invention;

Fig. 2 is a section of a furnace according to this invention which ismovable;

Fig. 3 is a section of the furnace of Fig. 2 moved to a new position;

Fig. 4 is a chart showing the heat content in kilocalories per gram atomor mole of magnesium, aluminum, and oxygen;

Fig. 5 is a graph showing the heat content in kilocalories mole ofmagnesium oxide and aluminum oxide;

Fig. 6 is a section of an oxy-magnesium torch;

Fig. 7 is a section of a blowpipe according to the inven tion; and

Fig. 8 is a chart of the flame characteristics of a blowpipe of thisinvention.

It is disclosed in the above-mentioned copending application that a hightemperature can be attained in and throughout an area by burningaluminum, magnesium or zirconium in the area. The metal is introducedinto the combustion area, such as the center of a furnace, where it ismixed with oxygen and combines to form an oxide in an exothermicreaction which releases a substantial quantity of heat. When thecombustion area is enclosed and the enclosing material is the propersubstance the continuous feeding of the metal brings about a combustionreaction which will continually increase in temperature. One of thecauses of this continual increase in temice perature is the productionof the metal oxide by the combustion reaction.

The importance of the nature of the substance composing the materialwhich encloses the combustion area can be understood in connection witha furnace according to this invention. By providing a furnace embodyingthis invention with a refractory or otherwise non-combustible materialthe combustion reaction of this invention can be brought about. Anexample of such a furnace material is the oxide of the burning metal,such as alumina in the case of aluminum. When a refractory ornon-combustible material delineates the combustion area and a combustilemetal of this invention is burned in the combustion area a reactiontakes place which accumulates and concentrates the heat of the reaction.A factor in this reaction is the oxide product of the reaction. has ahigh temperature during the reaction. It is also a refractory and thusprovides the reaction with its own refractory. The dissociationtemperature of this refrac tory oxide product is the limiting factor onthe increase of temperature. The dissociation point of the product ofcombustion depends upon the concentration of the products of combustionand the total pressure. For example, in burning aluminum thedissociation temperature of 3500 C. at atmospheric pressure can beincreased to 4000 C. at ten atmospheres and 4500 C. at one hundredatmospheres.

Another factor in this invention is the thermochemical equation of theburned metal. The thermochemical equations representing the combustionof magnesium and aluminum are as follows:

(1) Mg+ /2Oz- MgO 143,940 cal/mole at 25 C. (2) 2Al+l /2O2aA12Os 399,050caL/mole at 25 C.

Equation 1 indicates that l gram-atom of magnesium and /2 gram-mole ofmolecular oxygen under standard con ditions will release 143,940calories upon the magnesium and oxygen being reacted to form 1 mole ofmagnesium oxide. Similarly, Equation 2 indicates that 2 gramatoms ofaluminum and 1% moles of molecular oxygen form 1 mole of aluminum oxidewith the release of 399,- 050 calories. The calories released by thereactions represent the excess calories in the reactants magnesium,aluminum and molecular oxygen over the products magnesium oxide andaluminum oxide. This difference in calories may be expressed in terms ofthe heat content of the reactants and the combustion products. The heatcontent of a substance, as referred to here, relates to calories pergram-atom or gram-mole of the substance. In the operation of thisinvention the oxide produced in the combustion has a lower heat contentthan the reactants which form the oxide. Therefore, the formation of theoxide as shown in Equations 1 and 2 leaves a difference in heat contentwhich is the release of energy and provides the exothermic heat of thereaction.

In Fig. 1 a simple furnace is shown in which this invention may beoperated. An alumina pot-shaped sphere 10 is provided with an oxygensupply line 11 and a port 12. The port 12 provides an opening in theupper surface of the sphere 10. A rod 13 of aluminum is inserted intothe sphere 10 through the port 12. The rod 13 melting at its inner end14 feeds the combustion of alum-ition. As the combustion continues theadded heat from,

the exothermic reaction is retained to cause a further- This oxide kconcentration of heat. This increased concentration of heat is continuedas long as additional aluminum 1'3 is fed into the sphere to continuethe combustion reaction. The maximum temperature to which this processcan be raised is the dissociation of the combustion product. At thedissociation temperature the combustion product breaks down into itsseparate constituents.

In the sphere 10 the surface of the mass becomes raised to a temperaturewhere the burning aluminum 13 on the surface is formed into incandescentpieces 16. The rate of reaction can be partially controlled by the rateof feed of oxygen into the sphere =10 through the oxygen line 11. Theintroduction of pure oxygen is not necessary to the reaction. However,the closed nature of the sphere 10 requires a continuous supply of anoxidiling gas. A port suggested by dotted lines may be formed in thesphere 10 to expose the combustion reaction and the reactants. Thereaction radiates a high degree of energy, the advantages of which areset forth in greater detail below. This radiation may be utilized fromwithin the sphere 10 through the suggested port.

Another furnace embodying this invention is shown in Figs. 2 and 3. InFig. 2 a reactor 17 of alumina has a .port 18 closed by a removal plug19. The lower edge of port 18 is formed as a spout lip 20. The aluminumfeed is represented at 21 and the oxygen inlet at '22. Burning metal 23is shown resting on molten oxides 2*4 inside the reactor 17. In Fig. 3the reactor 17 is shown with the plug .19 removed from port 18 and themolten oxides 24 pouring over lip into a mold 25 carried on a movablesupport '26. A radiation shield 27 is shown. The reactor rotates on .anaxis perpendicular -to the plane of Fig. 3.

The port 18 is closed during the run by the plug 19 of the same materialas the furnaces reaction sphere 17. When sufiicient liquid oxide hasaccumulated, the plug 19 is withdrawn and the whole reactor 17 tilted(as shown in Fig. 3) to any desirable degree. After sufficient amountsof liquid oxide 24 have been poured out, the reactor '17 is returned toits original position.

A number of port holes 18 may he built into the reactory and liquidoxide poured out into various directions if desired.

It is not. essential that the reactor sphere be formed with axpre-formedhole as any suitable means for breach-- ing the reactor wall can be usedto release the liquid Product.

As a. further method, the melting of. the reaction sphere by means of a.high temperature torch may beused- The highest temperatures are producedby the hydrogen-fluorinetorch with temperatures about 4,000 C- At thesame time, the flux-ing and meltingv point depressingv action ofmagnesium or aluminum (or other metal) fluorides, produced by theinteraction of hydrogen fluoride and the metal oxide of the sphere,permits ready piercing of the shell. Instead of the expensive fluorine,chlorine trifiuoride (ClFz) may be used.

In the operation of this invention high temperatures are obtained alsoby heating the reactants before combustion. This preheating increasesthe heat content of the reactants as demonstrated. by the charts ofFigs. 4 and 5. The heat contents for magnesium, aluminum, oxygen,magnesium oxide and aluminum oxide are set forth in a temperature rangefrom 0 C including-the specific heats, heats of fusion, heats. ofvaporization, atomieand molecular weights as shown in Figs. 4' .and 5. IFigure 4 is a graph showing heat content of magnesium, alumimum, andmolecular oxygen in Kil'ocalories per gramatomor gram-mole plottedagainst degrees centigrade of temperature. Figure '5 is a graph showingheat content of magnesium oxide and aluminum oxide in Kilocalories pergram-mole plotted against degrees centigrade of temperature- Figures. 4and .5' show that at a. higher temperature the.

heat content of magnesium and alumi umis. greater in.

proportion to the heat content of magnesium and aluminum at a lowertemperature. Likewise, the differential between the heat content of thereactants and the heat content of the product is proportionallyincreased. As the amount of heat released by the combustion reactionincreases with an increase in the heat content differential, preheatingthe reactants will increase the heat produced from the reaction.

The following example illustrates the release of heat according to thisinvention:

EXAMPLE I One gram-atom of magnesium vapor heated to 2800 C. having aheat content of 48,910 calories per gram-atom is reacted with onegram-atom of molecular oxygen heated to 2800 C. having a heat content of9,800 calories per gram-atom to form magnesium oxide having 40,000calories per gram-mole and provide an exothermic heat of 1 8,700calories per gram-mole of magnesium oxide in addition to and above the143,940 calories per gram-mole generated at room temperature. Thus wehave, at a temperature level of 2800 C. to start with, a release of162,600 calories per 40.32 grams of magnesium oxide formed. I

The Example I and Figs. 4 and 5 are based on heat content data atatmospheric pressure. The temperature at which the combustion reactionmay take place with practicality can be further increased by placing thereac* tion space of the furnace under pressure. The following tableshows approximately the expected increase of the vaporizationtemperature or boiling point of magnesium, aluminum and aluminum oxidewith increase of pressure:

Table I Pressure in atmospheres 'bustion of aluminum in this invention.

Mg Al A1101 By placing a furnace operating according to this inventionunder pressure the temperature of vaporization is raised. Raising thetemperatures of vaporization in turn raises the temperature at which thecombustion reaction may be carried on and consequently the heat contentdifferential between the reactants and the products providing in turngreater heat in the reaction space.

As stated above the limit on the operation of this invention is thedissociation temperature of the product of the burned metal. As presenttemperature measurement apparatus has a recording limit in the region of2,000 Kelvin the actual temperature limit to this invention can only beestimated. At normal pressure of one atmosphere it is estimated atemperature of the magnitude of 3500 Kelvin can be obtained by the com-Zirconium will produce an even high temperature.

A furnace similar to the type shown and described in Figs. 1'3"has beenused to produce the temperatures of this invention. The followingexample demonstrates one such use and is set forth to merely illustratethe relation between the rate of feed of combustion materials and thevolumes of a suitable reactor:

EXA PL 1 500 grams-of aluminum were fed into a' reactor cornposedof twosemiespheres of alumina having an inside iame er of ix inch s an avolume of 1. 55 liters, Th aluminum was burned in pure oxygen, theoxygen was supplied and consumed at the rate of eightliters N. T. P. perminuteaud the combustion was continued fornineteen minutes. N, T. P.being the abbreviation for normal tern perature and pressure. At the endof this period 90 grams of unreacted aluminum was recovered in the formof a single lump in the sphere.

1 gram of aluminum generates 7410 calories in burning. In the reactionaluminum was burned at the rate of 21.6 grams per minute, or 160,000calories per minute. The reaction produced 86,300 calories per minuteper liter.

This example demonstrates the factors of the method of this invention.These factors include a rapid rate of feed of the combustion materialsand a combustion of these materials in a confined area surrounded by arefractory material which both provides insulation against the escape ofthe heat produced and resistance to the temperature of the heatproduced. The refractory material must therefore resist dissociation attemperatures over 1500 C. and preferably up to 3000 C. The refractorymaterial also must provide good insulation against the escape of theheat. It has been found that in burning metals such as aluminum,magnesium and zirconium in the method of this invention that arefractory material is produced which has the desired qualities for therefractory material which surrounds the combustion reaction.Consequently, the refractory produced by the combustion itself may beemployed to line the confined chamber and surround the combustionreaction.

Another factor in the production of the method of this invention is therelation of the volume of the reaction or combustion area to the rate offeed. The volume of the reaction area and the quantity of rate of feedof the combustion materials must provide an adequate con centration ofreactants per unit volume of the reaction or combustion area.

The essential elements for attaining the method and results of thisinvention are as follows:

1. A relationship between the volume of the reaction area and the rateof feed which produces temperatures in the range of 1500 C. to 3000 C.throughout the reaction area for a substantial period of time. Thevolume of the reaction area must be related to the quantity of feed soas to provide an adequate concentration of reactants per unit volume ofreaction area. The rate of feed of the combustion materials must besufiicient so as to provide adequate quantities of the reactants perunit of time per unit of volume of the reaction area to produce thetemperature conditions of this invention.

2. A wall structure which surrounds and confines the combustion area ofa thermal insulation which will retain the heat produced against rapidescape and resist dissociation at temperatures in the range of 1500 C.to 3000 C. The wall material must have a melting point in the range of1500 C. so that it does not melt before it can be replaced by thecombustion product of the combustion reaction. The following table setsforth representative wall structure materials and their melting points:

Table II MELTING POINTS "0.

A1203 2034 i 16 LazOz 2210 i: 20 ZrOz 2710 i 15 T1102 3220 i 50 SiOz1710 CaO 2570 MgO 2800 The thermal conductivity of refractory materialsVary according to physical state, generally, the more tightly packed anddense the material the higher the thermal conductivity. Conversely alower thermal conductivity is obtained from looser material. The thermalconductivity of the wall surrounding the area of combustion of thisinvention Will be of the order of the thermal conductivities of stone,brick, concrete, cement, and recognized refractories such as firebrickand alumina. The thermal conductivities of various othernon-combustibles are satisfactory for the operation of this invention.For example, cinder, concrete and granite will be effective as well asmore refractory materials.

It has been found that a material having a particularly low thermalconductivity can be formed by directing an oxy-aluminum torch flame onpure alumina. A sudden condensation of the alumina in the flame causesit to condense into a solid containing small spherical bubbles rangingin size from a few mm. in diameter down to less than 0.01 mm. Thisprovides a material having extremely low thermal conductivity for astructural material, and can be incorporated in the furnace wallsandwiched in-between higher thermal conductivity but structurallystronger layers.

As shown by Example II above, a rate of caloric production of high orderfor volume of reaction area may be achieved by this invention.Heretofore rates of caloric production per volume of reaction area havebeen sub stantially less than 20,000 calories per minute per liter.

An increase of the pressure under which the combustion reaction takesplace increases the dissociation temperature of the combustion product.The ultimate temperature obtainable is accordingly raised. In eachcombustion operation the dissociation temperature of the combustionproduct can be approached.

The heat of combustion of this invention may not only be applied in aconfined space within a fixed furnace. This invention may be employed inburning obtained by an oxy-aluminum, oxy-magnesium or oxy-zirconiumtorch. One form of an oxy-magnesium torch is shown in Fig. 6. The torch28 is made up of two coaxial tubes 29 and 30 together with a magnesiumchamber 31. The inner tube 29 supplies oxygen and is heated internallyby suitable heating elements 32 to a temperature above the boiling pointof magnesium. The admission of oxygen is suitably controlled by a valve33.

The outer tube 30 carries magnesium vapors from the chamber 31 to acombustion nozzle 34. The tube 30 is also heated by a set of elements35. Magnesium vapors are generated in the chamber 31 from a. magnesiumrod 36, suitably introduced into the chamber 31.. The torch 28 isinsulated in a jacket 37. The magnesium vapors are ignited at the nozzle34 and the oxygen is fed to the burning magnesium vapors at a controlledrate to provide a variable flame having a high temperature.

Another form of the metal-burning torch is shown in Fig. 7. In this forma blowpipe 38 has a feed pipe 39 and an oxygen tube 40. Oxygen is blowninto the pipe 38 through the .tube 40 while the metal to be burned isfed from feed 39 into the pipe 38 and into the oxygen jet from the tube40. The metal is introduced in powdered form and is carried in theoxygen stream to a nozzle 41 where the metal upon combustion burns witha flame.

The size of the particles of metal fed into the blowpipe 38 is criticalas is the rate of flow of oxygen. The particles must be small and enoughoxygen must be introduced at a high enough velocity to carry theparticles to the nozzle 41 and burn them briskly. In Fig. 8 a chartshows the flow of oxygen and the particle size for burning aluminum inthe blowpipe such as shown in Fig. 7. The mesh number of the aluminum isshown along the abscissa of the chart while the linear velocity of theoxygen in feet per second is shown along the ordinate of the chart. Atthe aluminum particle size of a mesh number of between 225 and 250 andlinear ve/ locity of the oxygen of from 15 to 35 feet per second astable flame can be produced. In the low oxygen velocity range as theparticle size is decreased the oxygen velocity must be slightlyincreased to prevent the flame from flashing back from the nozzle 11into the blowpipe 38. As the oxygen velocity is increased it isnecessary to decrease the particle size to prevent the flame fromblowing out.

A pilot light of ordinary city gas, or other suitable niting e i is n eary t ta he fl th or h. t i soper t d in an p p c Such an nitin deviceis not necessary if the torch starts operating in a confined spaceheated above the ignition temperature.

The torch that is provided by the combustion of aluminum, magnesium orzirconium as described above may be employed to produce a furnaceaccording to this invention. A furnace produced by the use of the metalburning torch embodies the features of the fur-. naces described above.

The metal burning torch may produce such a furnace for example in aconcrete or bricl: wall. A furnace may be produced in any body which hasa refractory reaction to the metal burning flame, where the metal isaluminum, magnesium, zirconium or a metal with similar burningcharacteristics. In using the torch to produce a. furnace according tothis invention in. a brick, cement or stone Wall, the torch fiame isused to cut out an opening in the wall. The opening in the wall becomesa confined area of combustion which encloses the torch flame and thecombustion. The combustion of the metal in the confined area bringsabout a concentration and acclumulation of heat similar to thatdescribed above in connection with the furnaces in Figs. 1 and 2. Thecombustion product from the torch flame in such an area has the sameaction and function as in the above described furnaces.

In the combustion reaction of this invention the combustion products andthe material enclosing the confined area of the combustion act to retainthe heat of combustion to the point where the (temperature exceeds themelting point of any known substance. The torch flame may [thus beemployed to melt and penetrate materials at a greater rate and withgreater ease than any implement has heretofore. For example, highlyrefractory bricks composed of pure alumina are melted down andpenetrated in less than a minute by an aluminum torch burning 100 gramsof aluminum powder per minute.

The production of high temperature which is a feature 7 of thisinvention is controlled and assisted by the rate of combustion of theburning metal. The rate of addition of the metal to the flame determinesthe temperature attained in the combustion area. This rate of additionhas .a critical point for attainment of the high temperatures which areprovided by this invention. A rate of feed of combustible metal of 100grams of aluminum per minute, for example, develops a temperature atwhich aluminum oxide is rapidly melted.

The advantage of this invention has been expressed in the description ofthe characteristics of the invention. The high temperatures producedaccording to this invention have a melting capacity which is adaptableto many uses. Also the radiation from the materials present in thecombustion chamber has a hitherto unknown intensity. This radiation hasseveral uses.

In describing this invention aluminum, magnesium and zirconium have beenselected as the metals for the preferred embodiment. it will beunderstood that other metals producing high temperature are alsoadaptable to this invention. Iron can be used as an addition to theabove described metals and also as a fiuxing agent. It will beunderstood that these and other modifications of the above describedembodiment can be made without departure from the spirit of thisinvention. Therefore it is intended that the scope of the invention belimited only by the scope of the appended claims.

I claim:

1. The method of producing heat above 1500" C. and up to 4500" C. by thecombustion of aluminum in a confined chamber made up of and surroundedby a re-- fractory material having a melting point above l500 C. and alow thermal conductivity which comprises introducing metallic aluminuminto the confined chamber at a rate of at least five grams per minuteper liter of said confined chamber introducing oxygen into said confinedchamber at :therate of at least 1.8 liters N. T. P. per minute per literof said confined chamber, contacting and mixing 5 grams of said aluminumper minute per liter of said chamber with 1.8 liters of said oxygen insaid confined chamber, igniting said mixture of oxygen and aluminum,burning said aluminum in said oxygen by oxidation to produce heat by theexothermic reaction of said burning at the rate of at least 20,000calories per minute per liter for at least five minutes producing heatby said burning of a temperature in excess of 1500" C., continuouslysupplying aluminum at a rate of 5 grams per minute per liter of saidconfined chamber retaining said heat of burning in said refractorychamber surrounding material, producing a molten oxide product of saidburning having a melting point of over 2000 C. and a low thermalconductivity, continuing to introduce said metallic aluminum and oxygeninto the combustion in said confined chamber at said respective rates,burning additional quantities of said metallic aluminum in said oxygencontact with said produced oxide product and at said rate to produceadditional heat at the rate of at least 20,000 calories per minute perliter. 7

2, The method of producing heat in a confined charm ber of refractorymaterial having a melting point of at least 1500" C. by producing moltenaluminum oxide in aid chamber at a temperature in excess of the meltingpoint of the refractory material which comprises introducing metallicaluminum into the confined chamber at a rate of at least 3 grams perminute per liter of said chamber, introducing oxygen into the confinedchamber at a rate of at least 3 grams of oxygen per minute per liter ofsaid chamber, contacting and mixing in said chamber at least 3 grams ofsaid aluminum per minute per liter with at least 3 grams per minute perliter of said oxygen, igniting said mixture, burning said aluminum insaid oxygen at a rate of at least 20,000 calories per minute per literof said chamber, continuously supplying said oxygen at a rate of atleast 3 grams per minute per liter of said'chamber to maintain burningof said aluminum-insaid oxygenat a rate of at least 20,000 calories perminute per liter to produce heat at a temperature in excess of 1500 (1.,continuously supplying and burning aluminum at a rate of at least 3grams per minute per liter of said chamber and producing molten aluminumoxide in said chamber at a temperature in excess of the melting point ofthe refractory material of said chamber.

3. Themethod of producing heat in a confined chamber of refractorymaterial having a melting point of at least 1500 C. by producing moltenaluminum oxide in said chamber at a temperature in excess of the meltingpoint of the refractory material which comprises introducing metallicaluminum into the confined chamber at a. rate of at least .3 grams perminute per liter of said chamber, introducing oxygen into the confinedchamber at a rate of at least 3 grams of oxygen per minute per liter ofsaid chamber, contacting and mixing in said chamber at least 3 grams ofsaid aluminum per minute per liter with at least 3 grams per minute perliter of said oxygen, igniting said mixture, burning said aluminum insaid oxygen at a rate of at 'least'20;000 calories per minute per literof said chamber, continuously supplying said oxygen at a rate of atleast 3 grams per minute per liter of said chamber to maintain burningof said aluminum in said oxygen at a rate of at least 20,000 caloriesper minute per liter to produce heat at a temperature in excess of 1500C continuously supplying and burning aluminum at a rate of at least 3grams per minute per liter, producing molten aluminum oxide by saidburning, contacting said chamber refractory material with said moltenoxide and continuously supplying aluminum and said gas to saidcombustion at said rate to produce sufficient aluminum oxide to meltsaid chamber refractory material.

4. The method of producing heat in a confined chamber of:refractory'material having a melting point of at least 1500 C. forproducing molten aluminum oxide in said chamber at a temperature inexcess of the melting point of the refractory material which comprisesintroducing metallic aluminum into the confined chamber at a rate of atleast 3 grams per minute per liter of said chamber, introducing oxygeninto the confined chamber at a rate of at least 3 grams of oxygen perminute per liter of said chamber, contacting and mixing in said chamberat least 3 grams of said aluminum per minute per liter with at least 3grams per minute per liter of said oxygen, igniting said mixture,burning said aluminum in said oxygen at a rate of at least 20,000calories per minute per liter of said chamber, continuously supplyingsaid oxygen at a rate of at least 3 grams per minute per liter of saidchamber to maintain burning of said aluminum in said oxygen at a rate ofat least 20,000 calories per minute per liter to produce heat at atemperature in excess of 1500" C., continuously supplying aluminum at arate of at least 3 grams per minute per liter, producing molten aluminumoxide by said burning, contacting said cham ber refractory material withsaid molten oxide and continuously supplying aluminum and oxygen to saidcombustion at said rate to produce suflicient aluminum oxide to meltsaid chamber refractory material.

5. The method of producing heat in a confined chamber of refractorymaterial having a melting point of at least 1500 C. by producing moltenoxide in said chamber at a temperature in excess of the melting point ofthe refractory material which comprises introducing a highly exothermicmetal selected from the group consisting of aluminum, magnesium andzirconium into the confined chamber at a selected rate of at least 3grams per minute per liter of said chamber for aluminum, at least 3.5grams per minute per liter of said chamber for magnesium, and at least 7grams per minute per liter of said chamber for zirconium, introducingoxygen into the confined chamber at a selected rate of 3 grams of oxygenper minute per liter of said chamber for aluminum and magnesium and 4.5grams of oxygen per minute per liter of said chamber for zirconium,contacting and mixing in said chamber said selected amounts of saidhighly exothermic metal and said oxygen, igniting said mixture, burningsaid highly exothermic metal in said oxygen at a rate of at least 20,000calories per minute per liter of said chamber, continuously supplyingsaid gas at said rate for said respective highly exothermic metal tomaintain burning of said selected highly exothermic metal in said oxygenat a rate of at least 10 20,000 calories per minute per liter to produceheat at a temperature in excess of 1500 C., continuously supplying andburning said selected highly exothermic metal at said respective rateper liter of said chamber and producing molten highly exothermic metaloxide in said chamber at a temperature in excess of the melting point ofthe refractory material of said chamber.

6. The method of producing heat in a chamber of refractory materialhaving a melting point of at least 1500 C. by producing in said chambermolten oxide of a metal of the group consisting of aluminum, magnesiumand zirconium at a temperature in excess of the melting point of therefractory material which comprises introducing a supply of a metal ofsaid group into the confined chamber at a rate of at least 12 grams ofsaid metal per minute per liter of said chamber, introducing oxygen intothe confined chamber of a rate of at least 3 grams of oxygen per minuteper liter of said chamber, contacting and mixing in said chamber atleast 12 grams of metal per minute per liter with at least 3 grams perminute per liter of said oxygen, igniting said mixture of oxygen andmetal, burning said metal in said oxygen at a rate of at least 20,000calories per minute per liter of said chamber, continuously supplyingsaid oxygen at a rate of at least 3 grams per minute per liter of saidchamber to maintain burning of said metal in said oxygen at a rate of atleast 20,000 calories per minute per liter to produce heat at atemperature in excess of 1500 C., and continuously supplying and burningsaid material at a rate of at least 12 grams per minute per liter ofsaid chamber and producing corresponding molten metal oxide in saidchamber at a temperature in excess of the melting point of therefractory material of said chamber.

References Cited in the file of this patent UNITED STATES PATENTS1,494,003 Malcher May 13, 1924 1,506,322 oNun Aug. 26, 1924 1,506,323ONeill Aug. 26, 1924 1,532,930 ONeill Apr. 7, 1925 2,277,507 Benner Mar.24, 1942 2,289,682 Rasor July 14, 1942 2,327,482 Aitchinson Aug. 24,1943 2,418,200 Smith Apr. 1, 1947 2,436,002 Williams Feb. 17, 1948

6. THE METHOD OF PRODUCING HEAT IN A CHAMBER OF REFRACTORY MATERIALHAVING A MELTING POINT OF AT LEAST 1500* C. BY PRODUCING IN SAID CHAMBERMOLTEN OXIDE OF A METAL OF THE GROUP CONSISTING OF ALUMINUM, MAGNESIUMAND ZIRCONIUM AT A TEMPERATURE IN EXCESS OF THE MELTING POINT OF THEREFRACTORY MATERIAL WHICH COMPRISES INTRODUCING A SUPPLY OF A METAL OFSAID GROUP INTO THE CONFINED CHAMBER AT A RATE OF AT LEAST 12 GRAMS OFSAID METAL PER MINUTE PER LITER OF SAID CHAMBER, INTRODUCING OXYGEN INTOTHE CONFINED CHAMBER OF A RATE OF AT LEAST 3 GRAMS OF OXYGEN PER MINUTEPER LITER OF SAID CHAMBER, CONTACTING AND MIXING IN SAID CHAMBER ATLEAST 12 GRAMS OF METAL PER MINUTE PER LITER WITH AT LEAST 3 GRAMS PERMINUTE PER LITER OF SAID OXYGEN, IGNITING SAID MIXTURE OF OXYGEN ANDMETAL, BURNING SAID METAL IN SAID OXYGEN AT A RATE OF AT LEAST